Parachute tow and release system with canopy extraction controlled by drag surface

ABSTRACT

In an embodiment, a parachute deployment system includes a parachute coupled to a release via a first load path. The first path includes crown lines. The release is adapted to attach the parachute to a rocket via the crown lines, and disengage the parachute from the rocket if a load shifts from the first path to a second path. The system also includes a line constrainer between the release and the parachute. The crown lines pass through the line constrainer, and the line constrainer is adapted to restrict an extent to which the crown lines are able to extend away from a longitudinal axis. An example release includes a back plate configured to couple a tow line to crown lines and a soft pin. The pin is adapted to separate from the back plate in response to tensioning of the release line, causing the parachute to disengage.

CROSS REFERENCE TO OTHER APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/951,987, now U.S. Pat. No. 10,099,792, entitled PARACHUTE TOW ANDRELEASE SYSTEM WITH CANOPY EXTRACTION CONTROLLED BY DRAG SURFACE filedApr. 12, 2018, which is a continuation-in-part of U.S. patentapplication Ser. No. 15/783,909, now U.S. Pat. No. 9,981,749, entitledPARACHUTE DEPLOYMENT SYSTEM USING DECOUPLED TOW AND RELEASE LINES filedOct. 13, 2017, both of which are incorporated herein by reference forall purposes.

BACKGROUND OF THE INVENTION

Aircraft or payload recovery may be required at low altitude, low speedconditions. For example, an aircraft may be hovering or transitioningbetween stages of flight and this transition (e.g., depending on flightconditions) can occur immediately after takeoff (e.g., on the order of afew meters). Low altitude conditions necessitate a parachute that openswith minimal altitude loss. Low speed conditions may present a lack of astrong airstream that can quickly inflate a parachute. In order to avoidhigh velocity impact and ensure occupant or payload safety, a parachutedeployment system is required that quickly extracts a parachute at lowaltitude, low speed conditions.

In some embodiments, a self-propelled projectile such as a rocket isused to quickly extract the parachute from the aircraft or otherpayload. The self-propelled projectile may present hazards or undesiredweight if left attached to the parachute following parachute extraction.The extra line length may also constrict or interfere with the canopy asit inflates. Releasing the self-propelled projectile at full extensionunder high line loads may result in parachute recoil, unpredictableparachute deployment, and/or altitude loss. New parachute systems whichwork with a self-propelled projectile but mitigate recoil when theprojectile and aircraft disconnect would be desirable.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the invention are disclosed in the followingdetailed description and the accompanying drawings.

FIG. 1 is a diagram illustrating an embodiment of a parachute deploymentsystem.

FIG. 2A is a diagram illustrating an embodiment of a parachutedeployment system in a stowed state.

FIG. 2B is a diagram illustrating an embodiment of a parachutedeployment system following rocket deployment.

FIG. 2C is a diagram illustrating an embodiment of a parachutedeployment system wherein the parachute is towed via a tow line.

FIG. 2D is a diagram illustrating an embodiment of a parachutedeployment system during release of a lower parachute line, canopy line,and/or suspension line restrainer.

FIG. 2E is a diagram illustrating an embodiment of a parachutedeployment system wherein the tow load imparted by the rocket istransferred to a release line.

FIG. 2F is a diagram illustrating an embodiment of a parachutedeployment system wherein the parachute is separated from a rocket.

FIG. 3 is a diagram illustrating an embodiment of a parachute deploymentsystem.

FIG. 4 is a flow diagram illustrating an embodiment of a parachutedeployment system process.

FIG. 5 is a flow diagram illustrating an embodiment of a parachutedeployment system process.

FIG. 6A is a diagram illustrating an embodiment of a release comprisinga latch and a cutter.

FIG. 6B is a diagram illustrating an embodiment of a release wherein arelease system restrainer is broken.

FIG. 6C is a diagram illustrating an embodiment of a release wherein alatch restrainer is broken.

FIG. 6D is a diagram illustrating an embodiment of a release wherein alatch is open.

FIG. 6E is a diagram illustrating an embodiment of a parachutedeployment system following separation of the parachute and a rocket.

FIG. 7 is a diagram illustrating an embodiment of a cutter.

FIG. 8 is a flow diagram illustrating an embodiment of a process to opena release.

FIG. 9A is a diagram illustrating an embodiment of a soft pin releaseassembly.

FIG. 9B shows another view of an embodiment of a soft pin releaseassembly.

FIG. 10A is a diagram illustrating an embodiment of a parachutedeployment system including a line constrainer associated with a firstarea, A1.

FIG. 10B is a diagram illustrating an embodiment of a parachutedeployment system including a line constrainer associated with a secondarea, A2.

FIG. 11A is a diagram illustrating an embodiment of a rectangular lineconstrainer.

FIG. 11B is a diagram illustrating an embodiment of a circular lineconstrainer.

FIG. 12A is a diagram illustrating an embodiment of a parachutedeployment system following rocket deployment.

FIG. 12B is a diagram illustrating an embodiment of a parachutedeployment system while the parachute is towed via a rocket tow line.

FIG. 12C is a diagram illustrating an embodiment of a parachutedeployment system during release of a lower parachute line restrainer.

FIG. 12D is a diagram illustrating an embodiment of a parachutedeployment system following the shifting of a load from a first loadpath to a second load path.

FIG. 12E is a diagram illustrating an embodiment of a parachutedeployment system following separation of the parachute from the rocket.

FIG. 12F is a diagram illustrating an embodiment of a parachutedeployment system with a fully deployed parachute.

FIG. 13 is a flow diagram illustrating an embodiment of a process tomanufacture a parachute deployment system including a line constrainer.

FIG. 14 is a diagram illustrating an embodiment of a conventionalparachute in a conventional packed state.

FIG. 15 is a diagram illustrating an embodiment of a parachute in asymmetrically packed state.

DETAILED DESCRIPTION

The invention can be implemented in numerous ways, including as aprocess; an apparatus; a system; a composition of matter; a computerprogram product embodied on a computer readable storage medium; and/or aprocessor, such as a processor configured to execute instructions storedon and/or provided by a memory coupled to the processor. In thisspecification, these implementations, or any other form that theinvention may take, may be referred to as techniques. In general, theorder of the steps of disclosed processes may be altered within thescope of the invention. Unless stated otherwise, a component such as aprocessor or a memory described as being configured to perform a taskmay be implemented as a general component that is temporarily configuredto perform the task at a given time or a specific component that ismanufactured to perform the task. As used herein, the term ‘processor’refers to one or more devices, circuits, and/or processing coresconfigured to process data, such as computer program instructions.

A detailed description of one or more embodiments of the invention isprovided below along with accompanying figures that illustrate theprinciples of the invention. The invention is described in connectionwith such embodiments, but the invention is not limited to anyembodiment. The scope of the invention is limited only by the claims andthe invention encompasses numerous alternatives, modifications andequivalents. Numerous specific details are set forth in the followingdescription in order to provide a thorough understanding of theinvention. These details are provided for the purpose of example and theinvention may be practiced according to the claims without some or allof these specific details. For the purpose of clarity, technicalmaterial that is known in the technical fields related to the inventionhas not been described in detail so that the invention is notunnecessarily obscured.

A parachute tow and release system with canopy extraction controlled bya drag surface is disclosed. The techniques described here includeparametrically tuning extension damping and air inflow to reduce recoiland decrease parachute inflation time. In some embodiments, a parachutedeployment system includes a parachute coupled to a release via a firstload path. The first load path includes parachute lines attached to acrown of the parachute. These parachute lines are called upper parachutelines or crown lines. The system includes a release adapted to attachthe parachute to a rocket via the upper parachute lines, and disengagethe parachute from the rocket if a load shifts from the first load pathto a second load path. The system includes a line constrainer providedbetween the release and the parachute. The upper parachute lines passthrough the line constrainer, and the line constrainer is adapted torestrict an extent to which the upper parachute lines are able to extendaway from a longitudinal axis of the parachute.

In various embodiments, the first load path further includes one or morelower parachute lines (also called suspension lines). The systemincludes a lower parachute line restrainer which, when released, permitsthe lower parachute line(s) to extend to full length. The full extensionof the lower parachute line(s) causes the load to shift from the firstload path to the second load path. The second load path includes arelease line that becomes taut when the load shifts. Consequently, theparachute is disengaged from the rocket via the release, the releaseline and upper parachute lines separate from the release, and the rocketassembly propels itself away from the main parachute assembly. In someembodiments, the upper parachute lines function as tow lines. That is,the same set of lines are both upper parachute lines and tow lines. Anexample of a parachute deployment system in which the upper parachutelines and tow lines are the same is shown in FIGS. 10A and 10B. Thesecond load path, in various embodiments, includes a release line.

First, some embodiments of a parachute system without a line constrainer(e.g., on or around the upper parachute lines) are described. Thisenables a simpler and/or clearer explanation of how the load shiftingfrom a first load path to a second load path enables a rocket to bereleased or otherwise decoupled from the parachute (e.g., without theadded complexity of having to discuss a line constrainer). Then, someembodiments of a parachute system with a line constrainer on the upperparachute lines are described. This enables the discussion of thoselater embodiments to focus more clearly and/or easily on those lineconstrainer embodiments and how they further improve the parachutesystem.

Quickly extracting the parachute using a rocket exerts a high load on atleast one line (e.g., the rocket tow line and also the upper parachutelines or crown lines) connecting the rocket and the parachute. Therocket is released or otherwise disconnected from the parachutefollowing parachute extraction for various reasons. For example, if therocket remains attached, it may present a fire hazard to the parachute,add undesirable weight to the parachute and payload, and/or cause theparachute to move in an undesirable and/or unpredictable manner. Theadditional line length may constrict the fabric of the canopy and mayprevent the parachute from opening freely. The manner in which therocket is released or otherwise disconnected from the parachute must becarefully considered. For example, severing (e.g., directly cutting) theline that connects the rocket and the parachute while the line is underhigh load (e.g., because the rocket is pulling the line taut) causes theline and/or parachute to recoil. Recoil of the parachute may result inunpredictable inflation, line tangling, and/or altitude loss, and istherefore undesirable.

The amount of recoil can be tuned according to the techniques describedhere. Recoil can be controlled by adjusting, for example, the amount ofdamping or drag induced by a surface moving through the air as theparachute is extracted or extended. A high level of damping correspondsto less recoil. A low level of damping corresponds to more recoil. Asmore fully described below, extension damping is tuned by controllingthe extent to which upper parachute lines are permitted to extend awayfrom a longitudinal axis of the parachute. Tunable extension dampingfinds application in a variety of flying conditions. For example, whenan aircraft is intended to fly relatively close to the ground, recoil isundesirable because the more recoil there is, the more likely that theaircraft will lose altitude and hit the ground. Thus, for low-flyingaircraft, the extension damping of the parachute can be tuned to havinga high level of damping. Conversely, for relatively high flyingaircraft, there is greater tolerance for altitude loss/recoil, and theextension damping can be tuned to have a relatively lower level ofdamping.

In some embodiments, a parachute deployment system comprises a tow line,a set of upper parachute lines (crown lines), a (e.g., separate) releaseline, and a line constrainer. The line constrainer is adapted torestrict an extent to which the upper parachute lines are able to extendaway from a longitudinal axis of the parachute. In some embodiments,restricting the extension of the upper parachute lines allows extensiondamping to be tuned to reduce recoil. In some embodiments, both the towand release lines are attached to a release which connects the rocketand the parachute and (e.g., at the appropriate time or condition)disconnects the rocket and the parachute from each other. In someembodiments, having a separate tow line and release line allows theparachute to be extracted quickly (e.g., using the tow line where thetow line is taut and the release line is slack) and the rocket to bereleased smoothly (e.g., when the release line becomes taut). In thedisclosed system, the tow line first takes the load of the payload. Thatis to say, the tow line is part of a load path that connects the rocketto the payload. The load path may comprise the tow line, upper lines ofthe parachute or crown lines, suspension lines of the parachute, and ariser of the parachute. In some embodiments, various parts of theparachute (e.g., the lines, the riser, etc.) are constructed of nylonbecause nylon is better for shock absorption. In some embodiments, therelease line is situated (e.g., runs) parallel to the tow line but isslack and bears no load (at least initially). A lower parachute linerestrainer (at least in some embodiments) is configured to release undera threshold force and may release after a canopy of the parachute isfully extracted. In some embodiments, release of the lower parachuteline restrainer causes the load to shift from the tow line to therelease line. For example, the release line begins to be pulled taut. Insome embodiments, the load is shifted by changing relative lengths ofthe lines. Due to the load on the release line, the release opens. Insome embodiments, the release opens under a small load. The opening ofthe release causes the rocket and the parachute to detach.

FIG. 1 is a diagram illustrating an embodiment of a parachute deploymentsystem. In the example shown, rocket 100 is tethered to release 104. Insome embodiments, rocket 100 is permanently attached or connected torelease 104. For example, release 104 is designed to remain with rocket100 following separation of rocket 100 and canopy 110. In variousembodiments, release 104 comprises a latch, a cutter, a pin, or anyother appropriate release. As will be described in more detail below,the release is designed to disconnect the rocket from the rest of theaircraft (including the parachute) with minimal recoil.

Tow line 108 is attached to release 104 at its upper end. At its lowerend, tow line 108 is attached to canopy 110 via the upper parachutelines. Upper parachute lines are attached to the canopy in the middle ofthe canopy, between an apex and outer edge of the canopy. In someembodiments, attaching the upper parachute lines to the middle of thecanopy or lower on the canopy than its apex allows lower sections of thecanopy to be pulled out quickly, which helps when the aircraft is at alow altitude, and provides even distribution of tension across all lowerparachute lines. In various embodiments, tow line 108 is attached tocanopy 110 using 4, 10, 20, or any appropriate number of upper parachutelines. The upper parachute lines are positioned equidistant around thecanopy. In some embodiments, the canopy is packed and initiallyextracted in an “M” cross-sectional shape which inflates more quicklythan a typical cylindrical shape. For example, the apex of the canopy ispacked in an inverted position.

Suspension lines 112 extend from canopy 110. In various embodiments,various numbers of suspension lines are used. A portion of thesuspension lines is folded up and held in lower parachute linerestrainer 116. In various embodiments, lower parachute line restrainer116 comprises a bight, a tied or sewed cloth, a thin plastic tube, acardboard loop, or any appropriate restrainer that holds the suspensionlines such that their lengths are effectively shortened. The lowerparachute line restrainer is configured to release under a thresholdforce (e.g., due to the rocket). For example, the lower parachute linerestrainer is configured to break, rip, tear, or open under thethreshold force. The suspension lines 112 and release line 114 areattached at their bottom ends to riser 117. In various embodiments,riser 117 comprises one line, multiple lines, or webbing. Riser 117 isattached to payload 118. In some embodiments, payload 118 comprises anaircraft.

In some embodiments, the release line is tied directly from the releaseto the bottom of the suspension lines. In some embodiments, the releaseline is tied to the apex, which in turn is tied to the center line. Thecenter line extends from an apex of the canopy to a confluence point atthe bottom of the suspension lines. In some embodiments, the releaseline is tied directly to the center line.

The following figures show examples of the exemplary parachutedeployment system at various points in time in order to betterillustrate how the parachute deployment system works and how it is ableto disconnect the rocket with little or no recoil.

FIG. 2A is a diagram illustrating an embodiment of a parachutedeployment system in a stowed state. In the example shown, a parachuteis stowed inside can 205A. Canopy 202A is folded and stored in the canalong with release 200A. The can is stored on or in payload 206A, whichmay comprise a cavity or compartment in an aircraft where the parachutedeployment system is stored. Rocket 204A is positioned externally to thecan.

FIG. 2B is a diagram illustrating an embodiment of a parachutedeployment system following rocket deployment. Upon triggering theparachute deployment system, rocket 204B begins traveling upwards awayfrom payload 206B. The rocket is attached to and tows release 200B.Release 200B in turn is attached to the parachute via tow line 208B andrelease line 210B. Canopy 202B remains folded inside of can 205B. It isnoted that in the state shown here, the tow line 208B is taut and therelease line 210B is slack.

FIG. 2C is a diagram illustrating an embodiment of a parachutedeployment system wherein the parachute is towed via a tow line. In theexample shown, canopy 202C has been extracted and is no longer in thecan (not shown). Rocket 204C tows release 200C. Release 200C is attachedto canopy 202C via tow line 208C and upper parachute lines (209C) whichare sometimes referred to as crown lines. Suspension lines 212C extendfrom canopy 202C and a portion of the lines is held in lower parachuteline restrainer 214C, shortening the effective lengths of the lines.Release line 210C extends from release 200C. Suspension lines 212C andrelease line 210C are attached to riser 216C.

As shown, rocket 204C is towing canopy 202C upwards via tow line 208Cand therefore tow line 208C is taut. Release line 210C is slack in thestate shown. In some embodiments, the length of release line 210C islonger than the combined length of the tow line, canopy length betweenthe tow line and suspension lines, and suspension lines held in lowerparachute line restrainer 214C. In this initial extraction state,neither the tow line nor the release line are under load. As the rockettravels further from the payload, the combined length of tow line 208C,suspension lines 212C, and riser 216C are pulled taut. Once that occurs,the portion of the canopy between the tow line and suspension lines isalso pulled taut. At this point, the parachute is fully extracted fromthe can. The rocket pulls upwards on the combined length while thepayload exerts a downwards force on the combined length due to inertia.The tow line is under load, whereas the release line remains slack andis not under load. The load path from the rocket to the payload travelsthrough the tow line, suspension lines held in the restrainer, and riserrather than traveling through the release line and riser because therelease line is longer in length than the combined length of the towline, suspension lines held in the restrainer, and intermediaries suchas the portion of the canopy between the tow line and suspension linesor lines used to attach the tow line to the canopy.

FIG. 2D is a diagram illustrating an embodiment of a parachutedeployment system during release of a lower parachute line, canopy line,and/or suspension line restrainer. For simplicity, a lower parachuteline restrainer is described in this example, but in other embodiments arestrainer is associated with a canopy line and/or suspension line(e.g., in addition to or as an alternative to a lower parachute line).In this example, the lower parachute line restrainer is configured torelease under a first threshold force. In some embodiments, the lowerparachute line restrainer is configured to release after the parachuteis fully extracted from the can. For example, the first threshold forceis equal to a force the lower parachute restrainer experiences in theevent the suspension lines are pulled taut. In some embodiments, thefirst threshold force is equal to a force that the lower parachute linerestrainer experiences in the event of sustained load on the suspensionlines. For example, the lower parachute line restrainer will not breakimmediately in the event the suspension lines are pulled taut, but ashort time after due to the forces exerted by the rocket and payload. Insome embodiments, the first threshold force is determined based onexperimental data. The type of lower parachute line restrainer may bechosen based on the first threshold force. The lower parachute linerestrainer may be calibrated based on the first threshold force. Forclarity, suspension lines 212D and lower parachute line restrainerpieces 218 and 220 are shown pulled to the side so that they are notobscured by release line 210D. In actuality, the suspension lines 212Dmay be pulled straight (e.g., between the rocket and payload) when thelower parachute line restrainer breaks or otherwise releases.

In the example shown, lower parachute line restrainer pieces 218 and 220have broken off of suspension lines 212D. The suspension lines as shownhave been released from their shortened position and released from theirtaut, shortened position. Tow line 208D is taut. Release line 210D isslack. As rocket 204D continues traveling upwards away from payload206D, both lines may first be slack because both are too long torestrain the rocket initially. As the rocket continues traveling or thepayload continues falling, load will eventually transition to releaseline 210D due to its shorter length compared to the longer combinedlength of the tow line, canopy portion, and suspension lines (no longershortened by the lower parachute line restrainer).

FIG. 2E is a diagram illustrating an embodiment of a parachutedeployment system wherein the tow load imparted by the rocket istransferred to a release line. It is noted that the parachute isn'tactually towed at this point. In the example shown, suspension lines212E are at their full, unrestrained length. The suspension lines 212Eare slack because the load has shifted to release line 210E such thatrelease line 210E is taut. The load path from rocket 204E to payload206E now comprises release line 210E and riser 216E. In someembodiments, the release line is attached to the center line and then tothe riser. The release line is shorter in length than the combinedlength of the length of tow line 208E, the upper parachute or crownlines (209E), the length of the portion of canopy 202E that is inbetween the tow line and the suspension lines, and the length of onesuspension line.

The release line is configured to open release 200E under a secondthreshold force. Some examples of the release are described in moredetail below. In some embodiments, the second threshold force is a lowforce. The second threshold force may be lower than the first thresholdforce required to release the lower parachute line restrainer. A desiredlevel of force for the second threshold force may be determinedexperimentally. In the event the release line is under the secondthreshold force, release 200E opens. In some embodiments, the opening ofrelease 200E allows the parachute and rocket to separate with little orno recoil.

FIG. 2F is a diagram illustrating an embodiment of a parachutedeployment system wherein the parachute is separated from a rocket. Inthe example shown, rocket 204F remains tethered to release 200F. Therocket and release are separated from the parachute and payload. Releaseline 210F and tow line 208F and upper parachute lines 209F dangle fromcanopy 202F. In some embodiments, canopy 202F completely fills followingdetachment of the rocket.

In some embodiments, a parachute deployment system includes othercomponents and/or is configured in some other manner not shown here. Thefollowing figure describes one such alternate.

FIG. 3 is a diagram illustrating an embodiment of a parachute deploymentsystem. In this example, the rocket 300 has an attached parachute 302that allows the rocket to float to the ground. The parachute may beinstalled for safety to prevent the rocket from impacting a person orobject at a high speed and causing damage.

In various embodiments, the parachute is towed from different points onits canopy and this figure shows an example different from that shown inthe previous figures. In this example, tow line 310 is attached at theapex of canopy 312. Canopy 312 is extracted in a roughly triangularcross-section shape.

In various embodiments, the lower end of the release line is attached atdifferent points. For example, the release line as shown is attached tothe payload directly. In some embodiments, the release line is attachedto a riser of the parachute.

In some embodiments, the lower parachute line restrainer restrains ariser of the parachute rather than suspension lines. In the exampleshown, lower parachute line restrainer 318 holds a riser of theparachute in a position such that its effective length is shortened. Forexample, loops of the riser are folded back and forth and secured.Release line 316 is longer than a combined length of the length of towline 310, a length from apex to opening of canopy 312, a length of onesuspension line of suspension lines 314, and the riser as restrained bylower parachute line restrainer 318. In the event lower parachute linerestrainer 318 is released, the release line is shorter the priordescribed combined length.

In some embodiments, the relative lengths concept remains the sameregardless of positioning of the release line, tow line, and lowerparachute line restrainer. For example, a first load path which includesthe tow line is initially longer than a second load path which includesthe release line. Following release of the lower parachute linerestrainer, the first load path is shorter than the second load path,which eventually causes the load path to change.

In some embodiments, the parachute deployment system includes a ripstitch (not shown here). A rip stitch is a fabric piece that is designedto rip in order to absorb shock when the parachute deploys, reducingline loading and thus reducing recoil. In some embodiments, a rip stitchis placed at the very bottom of the riser and/or at the bottom of thesuspension lines.

The following figure describes the examples above more generally and/orformally in a flowchart.

FIG. 4 is a flow diagram illustrating an embodiment of a process todeploy a parachute, including release of a rocket. At 400, a parachuteis towed by a rocket via a tow line. For example, the rocket beginstraveling upwards and away from the payload. As the rocket travelsupwards, a release is first pulled out from being stowed (e.g., therocket is attached to the release), followed by a canopy of theparachute, followed by suspension lines of the parachute. Eithersuspension lines or a riser of the parachute are held in a lowerparachute line restrainer. See, for example FIGS. 2A-2C.

At 402, it is determined whether to release a lower parachute linerestrainer. For example, a lower parachute line restrainer may bedesigned to release if the lower parachute line restrainer is subjectedto a force greater than a first threshold force. In the event the lowerparachute line restrainer is not subjected to a force greater than thefirst threshold force, the parachute continues to be towed by the rocketvia the tow line. For example, the rocket continues pulling upwards onthe tow line. The payload continues exerting a downwards force on thetow line. See, for example, FIG. 2C.

In the event it is determined to release the lower parachute linerestrainer, at 404 the lower parachute line restrainer releases, causingthe one or more lower parachute lines to release to their full lengths.In some embodiments, the lower parachute line restrainer effectivelyshortens the lengths of the one or more lower parachute lines and theyare restored to their full length following the release of the lowerparachute line restrainer. See, for example FIG. 2C where the lowerparachute lines are folded and tied using the lower parachute linerestrainer, which reduces their effective length. The release of thelower parachute line restrainer may comprise breakage, snapping,fraying, or any other release. The change in relative lengths causes thetow line to become slack (e.g., because its effective length increases).In some embodiments, the release line eventually becomes taut (e.g.,because the increase in the effective lengths of the lower parachutelines causes the load path which includes the release line to be shorterthan the load path which includes the now-released lower parachutelines).

At 406, it is determined whether a load switches from a first load pathwhich includes the tow line and the lower parachute lines to a secondload path which includes a release line. For example, because the lowerparachute lines are now released, that load path now has a longereffective length than the load path which includes the release line.Eventually, the load path which includes the release line will be pulledtaut, switching the load onto that line. See, for example, FIG. 2E.

In the event the load switches from the first load path which includesthe tow line and the lower parachute lines to the second load path whichincludes the release line, at 408 the release opens, permitting therocket and the parachute to separate. In some embodiments, the releaseline is configured to open the release if a second threshold force isexceeded (e.g., the tow line and release line are configured to separatefrom the release in the event the release line experiences a forcegreater than the second threshold force). For example, one or both ofthe lines may be released from a latch or cut using a cutter. Moredetailed examples of the release are described below.

In some embodiments, the release remains with the rocket. The tow lineand the release line separate from the release, allowing the parachuteto be separated from the rocket and released. See, for example, FIG. 2F.

The following figure provides some context for the process of FIG. 4(e.g., with respect to which line is bearing the load at various stepsin FIG. 4).

FIG. 5 is a flow diagram illustrating an embodiment of a parachutedeployment process with load-bearing context. In this example, contextfor various steps in FIG. 4 is provided, primarily with regard to whichline is bearing the load at various steps. In some embodiments, both thetow line and the release line are under no load at the beginning ofparachute extraction (e.g., before the rocket is ignited). Both linesare slack as the rocket begins to propel away from the payload. Two loadpaths are available that connect the rocket and the payload. A firstload path including the tow line is (initially) shorter than a secondload path including the release line (e.g., because one or more lowerparachute lines are wound up and tied, effectively shortening them). Asthe distance between the rocket and the payload reaches the length ofthe first load path, line elements in the first load path become tautand are under load. The second load path is not loaded and line elementsin the second path are slack. At 500, the tow line is under load andthere is no load on the release line. In the context of FIG. 4, step 500may describe step 400.

At 502, the lower parachute line restrainer releases, causing load totransfer to the release line. This step relates to steps 404 and 406 inFIG. 4. Release of the lower parachute line (see step 404 in FIG. 4)causes the first load path to be longer than the second load path byextending the (e.g., effective) length of a line element of the firstload path (e.g., a riser or suspension lines). In some embodiments, bothload paths are momentarily not loaded upon the extension of length ofthe first load path. As the distance between the rocket and the payloadreaches that of the second load path, either due to the payload droppingor the rocket propelling upwards, line elements in the second load pathsuch as the release line are pulled taut. See, e.g., step 406 in FIG. 4.In some embodiments, the second load path experiences only a small loadbefore triggering the release to open. The full line load of the towline may not be transferred to the release line.

At 504, the load on the release line causes the release to open. Seestep 408 in FIG. 4. In some embodiments, the lower parachute linerestrainer is configured to release when the parachute is fullyextracted. In quick succession, the release is subsequently opened whichallows separation of the rocket and parachute. The tow line experiencesa large load (e.g., which is good for deploying the parachute quicklyand at high speed and/or low altitudes) whereas the release lineexperiences a small load (e.g., which is good for little or no recoil)before quickly triggering release. Once the parachute is fullyextracted, the rocket is no longer needed.

At 506, the rocket and the parachute are separated. The rocket is safelyremoved without causing a rebound or reactionary movement from theparachute.

As described above, a release may comprise a variety of components. Thefollowing figures describe some examples where the release includes alatch and a cutter. For clarity, the exemplary release is described atvarious points at time.

FIG. 6A is a diagram illustrating an embodiment of a release comprisinga latch and a cutter. In some embodiments, release 104 of FIG. 1 isimplemented as shown here. In this example, the load on the release linecauses a cutter to be pulled downwards. The cutter is pulled down on aline, binding, or wrapper that holds a latch shut, causing the latch toopen. A tow line held in the latch is released.

In the example shown, cutter 600A and latch 610A are positioned adjacentto each other. Latch 610A as shown comprises a rectangular component anda curved component. Generally speaking, the latch is U-shaped with ahinge so that the curved part can swing away from the rectangular part.In this example, the curved part is shaped to provide a mechanicaladvantage such that the high tow line load can be reacted by a lowerlatch restrainer load on 604A. This allows the latch restrainer to besmaller, which makes it easier to cut (e.g., it lowers the cut and/orrelease load).

Latch restrainer 604A as shown holds latch 610A in a closed position(e.g., with all parts of the latch forming a continuous loop without anopening or break). For example, the latch restrainer clamps two top endsof the latch together so that the latch cannot open. Latch restrainer604A may comprise a line or a strip of fabric. In this example, latchrestrainer 604A is made of a material that is able to be cut with ablade, such as cotton or nylon.

In the example shown, latch restrainer 604A loops through cutter 600A.In some embodiments, latch restrainer 604A is exposed to a blade of thecutter through some other configuration or relative positioning of theblade and latch restrainer. For example, a blade is able to access andcut through the latch restrainer based on relative positions of thecutter and latch. In some embodiments, the latch restrainer is threadedthrough holes in the latch and/or cutter. For example, the latchrestrainer comprises a line that is threaded through a hole at the endof the rectangular component of the latch, a hole in an end of thecurved component of the latch, and through a hole in the side of thecutter.

In the example shown, release system restrainer 606A is positionedaround cutter 600A and latch 610A. In various embodiments, the releasesystem restrainer comprises a zip tie, a line, a strip of fabric, or anyappropriate restrainer which tears or releases when sufficient force orload is exerted downward on release line 608A and/or upward on line 602Ato the rocket. In some embodiments, the release system restrainermaintains the positions of the cutter and the latch relative to eachother. For example, latch restrainer 604A does not securely hold thepositioning of the cutter and the latch by itself. The release systemrestrainer holds the cutter in a position where the blade of the cutteris not in contact with the latch restrainer. In some embodiments, therelease system restrainer is configured to break or release under aspecific threshold force. In the event the specific threshold force isexerted on the release system restrainer, cutter 600A will move downward(e.g., due to tension in the release line) and cut latch restrainer604A, causing latch 610A to open. For example, the release systemrestrainer breaks in the event the release line is under the secondthreshold force.

Tether 602A is attached to the top of the latch 610A as shown andattaches the latch to a rocket. Tow line 612A is held inside of latch610A (e.g., tow line 612A is threaded through or around latch 610A). Insome embodiments, tow line 612A implements tow line 108 of FIG. 1. Asshown, the tow line has a loop at its end and the curved component ofthe latch is positioned in the loop. The tow line is not permanentlyattached to the latch. Release line 608A extends from the bottom ofcutter 600A. In some embodiments, release line 608A implements releaseline 114 of FIG. 1.

FIG. 6B is a diagram illustrating an embodiment of a release wherein arelease system restrainer is broken. In the event release line 608B isunder load, a force is exerted on the release system restrainer. In theevent the force exerted on the release system restrainer exceeds thespecific threshold force of the release system restrainer, the releasesystem restrainer breaks or releases. In the example shown, releasesystem restrainer pieces 614 and 616 have broken off. Cutter 600B andlatch 610B are shown in their positions immediately as the releasesystem restrainer is breaking off. In the example shown, latchrestrainer 604B remains intact.

FIG. 6C is a diagram illustrating an embodiment of a release wherein alatch restrainer is broken. In some embodiments, without the releasesystem restrainer intact, the cutter falls downwards relative to thelatch. For example, the cutter falls because it is being pulled byrelease line 608C and the latch is towed upwards by the rocket via line602C. In the example shown, cutter 600C drops in its position relativeto latch 610C, severing latch restrainer 604C. Following the severanceof latch restrainer 604C, cutter 600C remains attached to the parachutevia release line 608C but is no longer attached to latch 610C or therocket. Latch 610C remains tethered to the rocket via line 602C. At themoment shown, latch 610C is in a closed position.

FIG. 6D is a diagram illustrating an embodiment of a release wherein alatch is open. After the latch restrainer is cut, the latch opens (e.g.,the curved part of the latch has rotated about a hinge, causing it toseparate from the rectangular part of the latch). Latch 610D is shown inan open position. Tow line 612D as shown remains on the curved componentof latch 610D. As the rocket tows latch 610D up and away, tow line 612Dslips off of latch 610D. In some embodiments, a small additional load ontow line 612D causes the tow line to come off of latch 610D. Forexample, as the rocket continues flying and the payload continuesdropping, tow line 612D is pulled taut and pulled off from latch 610D.In various embodiments, the two halves of the latch may separate tovarious degrees (e.g., nearly 180° if desired) by adjusting orconfiguring the hinge as desired. In some embodiments, the two halves ofthe latch may separate completely after the latch opens.

Because the tow line 612D slips off of open latch 610D, there is verylittle recoil when the rocket separates from the parachute. In contrast,if a load path (e.g., bearing all of the load) were directly cut orotherwise severed, there would be a significant amount of recoil becauseof the tension or load on the line prior to the line being cut. Asdescribed above, a large amount of recoil is undesirable in someaircraft applications, which makes the techniques described hereinuseful.

FIG. 6E is a diagram illustrating an embodiment of a parachutedeployment system following separation of the parachute and a rocket.The example shown provides an overall view of the parachute deploymentsystem following opening of the release. In the example shown, rocket618 is attached to latch 610E. After separating, the rocket may tow thelatch for a distance and then begin to drop. In some embodiments, therocket has its own recovery system (e.g., a parachute).

Release line 608E and attached cutter remain attached to parachute 620.Tow line 612E (and upper parachute lines and/or crown lines) alsoremains attached to parachute 620. As shown, parachute 620 is completelyfilled and is attached to payload 622.

FIG. 7 is a diagram illustrating an embodiment of a cutter with achannel to thread the latch restrainer through. In various embodiments,the cutter is configured in different ways. In this example, vibrationsthrough lines, movement of the rocket/payload, or environmental factorssuch as wind may cause the blade of a cutter to come into contact withthe latch restrainer earlier than desired (e.g., when the release lineis not under load). To address this, the exemplary cutter shown here isconfigured to minimize chances of accidental severance of the latchrestrainer (e.g., caused by vibrations, slipping, etc.).

In the example shown, cutter 700 comprises a blade that is held in arecessed area within a frame. For example, blade 702 is secured suchthat it cannot rattle or move (e.g., prematurely) from its position inthe cutter. Latch restrainer 706 is threaded through a small channel orwindow in the cutter. Channel 704 is a slim opening through the cutterthat allows blade 702 to be pulled down on the latch restrainer and cutthe latch restrainer. Using a secured blade and a small channel ofaccess (e.g., through which the latch restrainer is threaded) decreasesthe chances of unintentional and/or premature cutting of the latchrestrainer.

FIG. 8 is a flow diagram illustrating an embodiment of a process to opena release. In some embodiments, the process is used at step 408 in FIG.4. At 800, the release system restrainer breaks. For example, therelease system restrainer breaks after a threshold force is exerted onthe release line. The release line may be under load following therelease of the lower parachute line restrainer, which changes the loadpath from one including the tow line to one including the release line.

At 802, the cutter is pulled down on the latch restrainer via therelease line. For example, the latch restrainer and cutter move relativeto each other, causing the blade of the cutter to cut the latchrestrainer.

At 804, the latch restrainer breaks. For example, the latch restrainermay be a line or tie that is cut. In some embodiments, the latch opensin the event the latch restrainer breaks. For example, in the previousfigures, the latch has a hinge and part of the latch falls open byrotating on the hinge.

As described above, a release may comprise a variety of components. Thefollowing figures describe some examples of a release having a soft pin.

FIG. 9A is a diagram illustrating an embodiment of a soft pin releaseassembly. Soft pin release assembly 940 is adapted to disengage a rocketfrom a parachute/payload. Soft pin release assembly 940 is an example ofhow release 104 of FIG. 1 can be implemented. FIG. 9B shows another viewof an embodiment of a soft pin release assembly.

The soft pin release assembly includes release back plate 944, soft pin954, first line 942, second line 946, guide loop 956, and break ties948. The soft pin release assembly is passively actuated when a load onrelease line 914 reaches a threshold force (also called a releaseforce). The soft pin release assembly exploits the rocket momentum andthrust when a parachute reaches a fully extracted state, actuating inresponse to the release force exerted by the rocket momentum and thrust.

In the example of FIGS. 9A and 9B, the release assembly is in anunactuated state. Release back plate 944 is structured to accommodatesoft pin 954. The release back plate can be made of an inflexiblematerial such as metal, plastic, and the like. The release back platecan be made of a flexible material such as nylon, webbing, and the like.Here, soft pin 954 is held in place against release back plate 944 by aloop of the second line 946 (that passes around a portion of the softpin 954 and through an opening of the release back plate), guide loop956, and break ties 948.

Soft pin 954 is adapted to minimize mass and inertial loading underacceleration, for example around 500-1000 g acceleration. Soft pin 954may be made of a flexible material such as cloth, rope, plastic, and thelike in order to achieve this property or performance. Unlikeconventional metal pins, a soft pin is able to avoid backing itself outof the release back plate. Referring to FIG. 9B, pin pigtails 952prevent the soft pin from backing itself out even when there is highinertial loading (e.g., load directed to the left of the soft pin). Insome embodiments, soft pin 954 is arranged such that approximately halfof the pin mass is on each side of guide loop 956 to prevent the pinfrom sliding in or out under inertial loads.

Guide loop 956 reacts to inertial loading of the soft pin (e.g., at500-1000 g) as the assembly is accelerated, and does not break. Guideloop 956 is adapted to guide the motion of the soft pin during actuationof the release as more fully described below. In some embodiments, theguide loop is made of a hard material or a ring.

Break ties 948 are adapted to retain the soft pin against the releaseback plate below the release force, and break in response to loading ofthe release line (e.g., at the release force). When a release force ismet or exceeded, release line 914 tensions, causing the break ties 948to break (not shown). Consequently, soft pin 954 slips away from therelease back plate 944, and crown lines 908 are disengaged from releaseback plate 944 and the first line 942. The rocket tow line 906 tows therocket away from the parachute/payload. Break ties 948 can be adapted torespond to a desired release force by selecting a material with adesired strength or by positioning the break tie at various locationsalong the release back plate.

This release assembly is an example of a two-ring release that reducesthe force needed to release compared with other types of assemblies. Thetwo-ring release includes two line lengths in series (here, first line942 and second line 946). Here, the force required for the pin to reactthe rocket tow force is around a quarter of the rocket tow force. When(around) the force required to break ties 948 and pull the pin isreached, the release is actuated. Break ties 948 break, allowing softpin 954 to slip away from release back plate 944, freeing crown lines908 and the parachute/payload to disengage from the rocket assembly withminimal recoil (e.g., which means less falling or dropping of anyattached aircraft or person before the parachute (re)inflates).

Also shown in FIGS. 9A and 9B are other components of a parachutedeployment system including crown lines 908, rocket tow line 906, andrelease line 914. These components are like those described in the otherfigures unless otherwise described here. Referring to FIG. 10A, rockettow line 1002 corresponds to rocket tow line 906 of FIG. 9. Returning toFIG. 9, crown release lines 908 are individually looped through firstline 942 as shown. First line 942 is looped through second line 946,which is then looped through soft pin 954 to keep the soft pin in placewhen the release is in an unactuated state as shown. In someembodiments, the crown lines are made of a low mass material to decreaseand avoid interference with fast inflation after release.

Bridle 962 is arranged to run from the rocket tow line to a rocketparachute. In a stowed state, the bridle is tucked inside the parachutecanopy such as canopy 110 of FIG. 1. The bridle runs to a rocketparachute such as parachute 302 shown in FIG. 3. The rocket parachutecanopy is tucked inside a main parachute canopy.

Rocket tow line 906 runs from the release back plate to the rocket. Whenthe release is actuated, the rocket tow line remains coupled to therocket, and pulls the release back plate away from the crown lines 908to free the parachute/payload from the rocket assembly including theback plate with minimal recoil.

Release line 914 runs between soft pin 954 and a parachute centerlinethat runs from the parachute apex to the suspension line confluencepoint. When a rocket is deployed, the release line is extended as morefully described with respect to FIGS. 2A-2F. In response to tensioningof the release line, the release is actuated by the breaking of thebreak ties 948. In various embodiments, the release line has ample slackto avoid actuating the release prematurely.

In contrast to the release shown in FIGS. 6A-7, the release of FIGS. 9Aand 9B does not require a cutter, which may reduce the weight andincrease the reliability of the parachute deployment system. In variousembodiments, the soft pin release assembly is tolerant of packing underpressure in a can, which facilitates minimization of stowed parachutevolume and clean packaging. The soft pin release assembly, in variousembodiments, tolerates chaotic extraction and snatch from the can, anddoes not release prematurely due to rips, tears, or inertial loads. Forexample, the soft pin release assembly is agnostic to rotation. Onrelease, the soft pin release assembly avoids tangling and snags. In analternative embodiment, the release assembly is implemented by a snapshackle.

The following figures show examples of a parachute tow and releasesystem with canopy extraction controlled by drag surface, e.g.,controlled drag during parachute extraction. A parachute initiatesinflation prior to beginning its downward fall by allowing air to flowin through the parachute crown and spread the skirt for easier inflationonce the downward stroke begins. The period during which the parachuteis extracted and air flows in through the crown is called the extensionstroke, and the beginning of the falling is called the downward stroke.The release mechanism disclosed accommodates high extraction speeds inwhich the parachute is extracted at around 50-100 mph relative to theairstream. Typically, fast extraction of the parachute causes theparachute to slam against its full extension point, which in turn loadsthe lines of the parachute and causes recoil. Recoil causes a payload tolose altitude, which is undesirable because of potential payload damageor loss and less time or height for the parachute to slow down anyattached aircraft or person. The techniques described here allow controlof the extension of the parachute.

In one aspect, the extension stroke can be damped by controllingextension (e.g., in a radially outwards direction) of upper parachutelines. In some embodiments, extension damping is tunable by providing aline constrainer. Example line constrainers are shown in FIGS. 10A and10B. Because the type/level of damping can be selected or otherwisecontrolled to some degree, the parachute need not extend with a largeamount of momentum and slam against its extension point. Instead, theextension stroke is controlled and the parachute can be extended moreslowly towards its extension point. The level of extension is aparameter that can be set or selected.

The following figures show examples of an exemplary parachute deploymentsystem having a line constrainer. The line constrainer restrictsextension of upper parachute lines to provide a desired level ofextension damping.

FIG. 10A is a diagram illustrating an embodiment of a parachutedeployment system including a line constrainer associated with a firstarea, A1. In the example shown, the system includes rocket 1000, release1004, line constrainer 1020, and parachute 1010. Each of the systemcomponents function like those of FIG. 1 unless otherwise describedhere.

Rocket 1000 is adapted to extract the parachute from a container. Forexample, in an unactuated state, the parachute is stored in a cavity orcompartment in payload 1018. Prior to deployment, the parachute may befolded inside the cavity, as more fully described with respect to FIGS.14 and 15. To actuate the parachute, the rocket deploys and pulls theparachute from the container. The momentum of the rocket causes release1004 to actuate at desired conditions, separating the rocket from theparachute (as described above).

Release 1004 is adapted to disconnect rocket 1000 from parachute 1010with minimal recoil. The level of extension damping or drag duringparachute extraction can be adjusted by selecting certain parameters orcharacteristics of the line constrainer 1020 as will be described inmore detail below. When the load pulls on the release, the releasecauses the parachute to detach from the rocket. The conditions thatcause the release to disengage the parachute from the rocket is morefully described with respect to FIG. 12E. In various embodiments, therelease includes a latch, a cutter, a pin (e.g., a soft pin), or thelike. In the example shown, rocket 1000 is connected to release 1004 viarocket tow line 1002. In some embodiments, rocket 1000 is permanentlyattached or connected to release 1004. For example, release 1004 isdesigned to remain with rocket 1000 following separation of rocket 1000and parachute 1010. The release can disengage from the parachute in avariety of ways as described with respect to release 104 of FIG. 1 andFIGS. 6A-9B.

Parachute 1010 is adapted to facilitate smooth flight of payload 1018.For example, the parachute is used to help a payload such as an aircraftgently land at a desired location. Parachute 1010 includes a canopy,upper parachute lines 1008, and lower parachute lines 1012 (also calledsuspension lines). In this example, the upper parachute lines alsofunction as tow lines, and the two terms are used interchangeably. Insome embodiments, the tow line is separate from the upper parachute linesuch as in the system of FIG. 1. Tow line 1008 are adapted to tow theparachute, which is different from the rocket tow line 1002 adapted totow the rocket.

Tow line 1008 is attached to release 1004 at its upper end. At its lowerend, tow line 1008 is attached to a canopy of parachute 1010. Incontrast to the example of FIG. 1, here the upper parachute lines 1008are directly attached to the release. When the parachute is releasedfrom release 1004, each of the upper parachute lines individuallydetaches from the release. This decreases the mass upstream of theparachute that could potentially interfere with the opening of theparachute.

In various embodiments, the upper parachute lines are attached to thecanopy in the middle of the canopy, between an apex and outer edge ofthe canopy. In some embodiments, attaching the tow line to the middle ofthe canopy or lower on the canopy than its apex allows lower sections ofthe canopy to be pulled out quickly, providing even distribution oftension across lower parachute lines. In some embodiments, the canopy isstored in the can in a manner that allows the canopy to inflate quicklyas described with respect to FIGS. 14 and 15. The ability to quicklyextract and inflate the parachute may be especially helpful at lowerflight altitudes (e.g., on the order of a few meters), where a delay inparachute inflation may cause a payload (e.g., an attached aircraft orperson) to be damaged or lost.

Suspension lines 1012 allow a payload to be suspended from theparachute. Here, the suspension lines 1012 and a release line (notshown) are attached at their bottom ends to riser 1017. Riser 1017attaches payload 1018 to parachute 1010 via lower parachute lines 1012.Payload 1018 may be any object benefitting from a parachute such as anaircraft, package, human, and the like. In some embodiments, the releaseline is tied to an apex of canopy 1010, which in turn is tied to thecenter line, which is tied to the riser.

In various embodiments, a portion of the suspension lines is held in alower parachute line restrainer (not shown) such that the length of thesuspension lines is shortened, as more fully described with respect toFIG. 12B. For example, the lower parachute line restrainer can beimplemented by a bight, a tied or sewed cloth, a thin plastic tube, acardboard loop, or the like. The lower parachute line restrainer isconfigured to release under a threshold force (e.g., due to the rocketpulling away from the parachute). For example, the lower parachute linerestrainer is configured to break, rip, tear, or open when subjected tothe threshold force.

The number of upper parachute lines, suspension lines, and riser linescan be selected based on the payload or flight conditions. For example,several upper parachute lines (2, 4, 10, 20, or more) can be positionedequidistantly on the canopy. More lines may attach components moresecurely to each other, but would be heavier than fewer lines. In someembodiments, riser 1017 is implemented by a webbing.

Line constrainer 1020 is adapted to restrict an extent to which theupper parachute lines are able to extend away (e.g., radially outward)from a longitudinal axis (dashed line A1) of the parachute. In variousembodiments, the amount of extension damping is directly proportional toan area defined by the extent of the upper parachute lines. In FIG. 10A,the cross-sectional area of the dashed horizontal line through lineconstrainer 1020 is A1.

FIG. 10B is a diagram illustrating an embodiment of a parachutedeployment system including a line constrainer associated with a secondarea, A2. The example system shown in FIG. 10B includes the samecomponents as the system of FIG. 10A unless otherwise described here.Line constrainer 1030 restricts an extent to which the upper parachutelines are able to extend away from a longitudinal axis of the parachuteto area A2. A2 is smaller than A1 because line constrainer 1030restricts movement of the upper parachute lines to a greater degreecompared with line constrainer 1020. In various embodiments, the dampingdrag force is proportional to the area corresponding to the extent towhich upper parachute lines are able to extend away from a longitudinalaxis of the parachute. Thus, the system in FIG. 10A has higher dampingcompared with the system in FIG. 10B.

There are many advantages to using the line constrainer to restrictmovement of the upper parachute lines to parametrically tune extensiondamping. In one aspect, extension damping is tunable. This allows asystem to be adapted for a variety of flight situations. For example, ifan aircraft (payload of the parachute and rocket system) is expected tofly at relatively low altitude, then the line constrainer can beadjusted or sized to constrain the upper parachute lines to movementwithin a larger area, which corresponds to high damping. Unlikeconventional means to constrain lower parachute lines, the lineconstrainers in the examples shown in FIGS. 10A and 10B constrain theupper parachute lines.

The sizing of a cutout in the line constrainer controls how much airpasses through a mid-channel of the parachute. The shape of the canopydue to airflow through the canopy helps the parachute to inflate morequickly. For example, the larger cross-sectional area A1 of FIG. 10Arelative to the cross-sectional area A2 of FIG. 10B means that theparachute of FIG. 10A will inflate more quickly when a similarly sizedcutout allows air to pass through the line constrainer into the canopyon extraction. The operation of the parachute deployment system is morefully described with respect to FIGS. 12A-12F.

The line constrainer can be implemented by various materials. Forexample, the line constrainer can be made of a flexible material withholes through which the upper parachute lines pass. The line constrainercan be made of a rigid material. The line constrainer can be a varietyof shapes such as a disk, polygon, or the like. In some embodiments, theline constrainer includes a cutout to promote airflow to facilitatequick parachute inflation. For example, the line constrainer can be aring or other shape with a cutout. The following figures show examplesof the line constrainer.

FIG. 11A is a diagram illustrating an embodiment of a rectangular lineconstrainer. In FIG. 11A, the line constrainer is rectangular with arectangular cutout 1104. FIG. 11B is a diagram illustrating anembodiment of a circular line constrainer. In FIG. 11B, the lineconstrainer is circular with a circular cutout 1106.

The body of the line constrainer can be made of various materials. Insome embodiments, the line constrainer is made of a flexible materialsuch as nylon. For example, grommets in the line constrainer for linepass-through can be made of metal. In some embodiments, the lineconstrainer is made of an inflexible material such as metal or hardplastic with spaces for line pass-through. The cutout 1104 allows air toflow through the line constrainer. The cutout can be open, mesh, or thelike.

In the embodiments shown here, grommets are provided on the lineconstrainer to guide crown lines into place in a parachute deploymentsystem. For example, referring to FIG. 10A, a line constrainer such asthe ones shown in FIGS. 11A and 11B is provided between a release 1004and parachute 1010. Crown lines 1008 pass through the grommets of theline constrainer to (removably) couple the parachute to the release1004. Returning to FIGS. 11A and 11B, four grommets 1102 are providedalong the perimeter of the line constrainer. For example, the grommetsmay be provided near (e.g., within some threshold distance of) theperimeter. Although this example shows four grommets, any number ofgrommets (e.g., suitable for the number of crown lines in the parachutedeployment system) may be provided.

The sizing of the line constrainer affects the level of extensiondamping. In various embodiments, the outer diameter (or perimeter) isproportional to a level of damping (because in these examples at least,the grommets are positioned near the outer diameter of the lineconstrainers shown). As discussed with respect to FIGS. 10A and 10B, arelatively large area bounded by the line constrainer causes higherdamping than a smaller area. Thus, a line constrainer with a relativelylarger diameter (or perimeter) causes higher damping than a lineconstrainer with a smaller diameter (or perimeter).

The sizing of the (e.g., center) cutout of the line constrainer affectsthe amount of air inflow through the line constrainer to the canopycausing the canopy to inflate. In various embodiments, the cutout 1104is sized based on a desired level of air inflow. A relatively largercutout permits more air inflow than a smaller cutout. The desired airinflow may depend on the size of a parachute canopy. Typically a smallerparachute requires less air flow to inflate than a larger parachute. Thedesired air inflow may depend on a target speed of parachute inflation.More air inflow permits a parachute to be inflated more quickly.Referring to FIGS. 11A and 11B, cutout 1104 is smaller than cutout 1106.Thus, a canopy of the same size would inflate more quickly than in asystem that has the line constrainer shown in FIG. 11B compared withFIG. 11A. The shape of the cutout shown here is merely exemplary and isnot intended to be limiting. The cutout can be sized to permit a desiredvolume of air inflow.

The following figures show examples of the exemplary parachutedeployment system at various points in time in order to betterillustrate how the parachute deployment system works and how it is ableto disconnect the rocket with tunable extension damping (e.g., little orno recoil).

FIG. 12A is a diagram illustrating an embodiment of a parachutedeployment system following rocket deployment. In this state ofdeployment, rocket 1200 begins traveling away from can 1218 (here,substantially up), causing release 1204 (which is coupled to the rocketvia rocket tow line 1202) to be pulled out from the can. The release isattached to the parachute via tow line 1208 and the release line (notshown). In this example, the crown lines are the same as the tow lines.Parachute 1210 remains stowed inside can 1218. In some embodiments, thecanopy of the parachute is stored in the can in the manner more fullydescribed with respect to FIGS. 14 and 15. The can is stored on or in apayload of the rocket. The can may comprise a cavity or compartment inan aircraft where the parachute deployment system is stored.

FIG. 12B is a diagram illustrating an embodiment of a parachutedeployment system while the parachute is towed via a tow line. In thisstate of deployment, the rocket continues traveling away from can 1218,causing parachute 1210 to be pulled out from the can. This state issometimes called the “initial extraction state.” As shown, the extent towhich the crown lines 1208 are able to extend away from a longitudinalaxis of the parachute is restricted by line constrainer 1220. The lowerparachute lines 1212 extend from the skirt of the parachute, and aportion of the lower parachute lines is held in lower parachuterestrainer 1216, shortening the effective lengths of the lines. Thelower parachute lines 1212 and release line 1214 are coupled to riser1217.

In this state, the tow line 1208 is taut and the release line 1214 isslack. In some embodiments, the length of release line 1214 is longerthan the combined length of the crown line 1208, canopy length betweenthe crown line and lower parachute lines, and lower parachute lines heldin lower parachute line restrainer 1216. In this initial extractionstate, neither the tow line nor the release line are under load exceptfor the load on the tow lines required to pull the canopy out of thecan.

As the rocket travels farther away from the payload, the combined lengthof tow line 1208, suspension lines 1212, and riser 1217 are pulled taut.In response, the portion of the canopy between the tow line and lowerparachute lines is also pulled taut. At this point, the parachute isfully extracted from the can. The rocket pulls upwards on the combinedlength while the payload exerts a downwards force on the combined lengthdue to inertia. The tow line is under load, whereas the release lineremains slack and is not under load. The load path from the rocket tothe payload travels through the tow line, suspension lines held in therestrainer, and riser rather than traveling through the release line andriser because the release line is longer in length than the combinedlength of the tow line, suspension lines held in the restrainer, andintermediaries such as the portion of the canopy between the tow lineand suspension lines or lines used to attach the tow line to the canopy.

FIG. 12C is a diagram illustrating an embodiment of a parachutedeployment system during release of a lower parachute line restrainer.In this example, the lower parachute line restrainer is configured torelease under a first threshold force. The lower line restrainer 1216breaks into pieces as shown to allow the lower parachute lines to extendto their full lengths. In some embodiments, the lower parachute linerestrainer is configured to release after the parachute is fullyextracted from the can. For example, the first threshold force is equalto a force the lower parachute restrainer experiences in the event thelower parachute lines are pulled taut. In some embodiments, the firstthreshold force is equal to a force that the lower parachute linerestrainer experiences in the event of sustained load on the suspensionlines. For example, the lower parachute line restrainer will not breakimmediately in the event the suspension lines are pulled taut, but ashort time after due to the forces exerted by the rocket and payload. Insome embodiments, the first threshold force is determined based onexperimental data.

The type of lower parachute line restrainer may be chosen based on thefirst threshold force. The lower parachute line restrainer may becalibrated based on the first threshold force. For clarity, lowerparachute lines 1212 and lower parachute line restrainer pieces areshown pulled to the side so that they are not obscured by the releaseline. In various embodiments, the lower parachute lines may be pulledstraight (e.g., between the rocket and payload) when the lower parachuteline restrainer breaks or otherwise releases.

In the example shown, lower parachute line restrainer pieces have brokenoff of lower parachute lines 1212. The suspension lines as shown havebeen released from their taut, shortened position. The tow line is taut,and the release line is slack. As the rocket continues traveling upwardsaway from the payload, both lines may both be slack because both are toolong to restrain the rocket initially. As the rocket continues travelingor the payload continues falling, load will eventually transition to therelease line due to its shorter length compared to the longer combinedlength of the tow line, canopy portion, and lower parachute lines (nolonger shortened by the lower parachute line restrainer). Forsimplicity, a lower parachute line restrainer is described in thisexample, but in other embodiments a restrainer is associated with acanopy line (e.g., in addition to or as an alternative to a lowerparachute line).

FIG. 12D is a diagram illustrating an embodiment of a parachutedeployment system following the shifting of a load from a first loadpath to a second load path. Here, the load shifts to release line 1214.In the example shown, the lower parachute lines are at their full,unrestrained length. The lower parachute lines are slack because theload has shifted to release line 1214 such that the release line istaut. The load path from the rocket to the payload now includes releaseline 1214 and the riser. As described above, in some embodiments, therelease line is attached directly from the release to the bottom of thesuspension lines. In other embodiments, the release line is attached thecenter line and then to the riser. The release line is shorter in lengththan the combined length of the length of the tow line, the crown lines,the length of the portion of canopy that is in between the tow line andthe lower parachute lines, and the length of one lower parachute line.

The release line is configured to actuate release 1204 under a secondthreshold force. Some examples of the release are described in moredetail with respect to FIGS. 6A to 9B. In some embodiments, the secondthreshold force is lower than the first threshold force (e.g., the firstthreshold force is the force to release the lower parachute linerestrainer). In some embodiments, actuation of the release allows theparachute and rocket to separate with little or no recoil.

FIG. 12E is a diagram illustrating an embodiment of a parachutedeployment system following separation of the parachute from the rocket.In this example, as part of the actuation of the release, each of thecrown lines individually release to minimize mass inhibiting inflationof the parachute. Although line constrainer 1220 is shown attached tothe release here, in other embodiments, the line constrainer may simplydetach and fall off. In the example shown, the rocket remains tetheredto the release. The rocket and release are separated from the parachuteand payload. In various embodiments, the release line and crown (tow)line remain attached to the canopy of the parachute. In someembodiments, the canopy completely fills following separation from therocket as shown in FIG. 12F.

Although in this example, crown lines 1208 is pictured as beingrelatively short, the crown lines may instead by sized of sufficientlength to allow full deployment of the parachute canopy without beingconstrained by the crown lines. For example, when the rocket and/orrelease malfunctions (e.g., rocket fails to release), the canopy is ableto completely fill because the crown lines are of sufficient length toallow the canopy to fully open. When a rocket release failure isdetected, a line constrainer (if one is used) slips axially upward tothe top of the crown lines, and crown lines are permitted to extend tofull length to facilitate full filling of the canopy. In other words,the crown lines extend without interfering with full inflation of thecanopy.

FIG. 12F is a diagram illustrating an embodiment of a parachutedeployment system with a fully deployed parachute. The end of parachuteextraction is sometimes called an “end stroke,” and the beginning of theparachute falling is called a “down stroke.” FIG. 12E shows a parachuteend stroke, and FIG. 12F shows a parachute down stroke. There is littleor no recoil on the end stroke. The line constrainer allows the level ofdamping of the end stroke to be controlled. In various embodiments, therelease line 1214 and crown (tow) lines 1208 remain attached to thecanopy 1210 of the parachute as shown.

In some embodiments, the extent to which crown lines are able to extendaway from a longitudinal axis of a parachute of a parachute deploymentsystem can be limited without a line constrainer. For example, fixedcrown line lengths produce a desired cross-sectional area withoutneeding to provide a line constrainer.

FIG. 13 is a flow diagram illustrating an embodiment of a process tomanufacture a parachute deployment system including a line constrainer.The process can be implemented by a parachute deployment systemassembler, such as a programmed robotic arm or by manual efforts. Theprocess can be used to manufacture a parachute deployment such as theone shown in FIGS. 10A and 10B.

At 1300, a parachute is coupled to a release via a first load path.Referring to FIG. 10A, parachute 1010 is coupled to release 1004 via afirst load path. The first load path is made up of crown lines 1008. Theparachute can be removably coupled to the release such that theparachute is separated from the release (and rocket) during parachutedeployment as described here. Examples of the release are shown in FIGS.6A-9B.

In various embodiments, coupling the parachute to the release includesassembling a parachute system (such as the one shown in FIGS. 10A and10B) for extraction via a load path through the upper parachute lines,canopy, and suspension lines, and for release via a release line. Therelease line length may be tuned so that substantially all tension istaken through the release line when the extraction load path isunconstrained. The suspension line restrainer size can be tuned to leaveample slack in the release line when the extraction load path is undertension.

Returning to FIG. 13, at 1302, a line constrainer is coupled between therelease and the parachute. The line constrainer restricts an extent towhich crown lines are able to extend away from a longitudinal axis ofthe parachute. The extension of the crown lines can be selected based ona desired level of extension damping. As more fully described withrespect to FIGS. 10A and 10B, greater extension of the crown linescorresponds to greater extension damping. In various embodiments, theline constrainer includes grommets through which crown lines areextended. One end of the crown lines is coupled to the release, and theother end of the crown lines is coupled to the canopy of the parachute.

The line restrainer is installed on the upper parachute lines above thecanopy, where the line constrainer is able to restrict an extension ofthe upper parachute lines radially outward away from the longitudinalaxis of the parachute system. In various embodiments, the components ofthe parachute system including the release are integrated withconnections and ties prior to packing the parachute into acontainer/can.

In various embodiments, the parachute deployment system is packed into acan. The parachute is stored in an un-deployed state, and is extractedin the sequence shown in FIGS. 2A-2F or FIGS. 12A-12F. The parachute canbe stored in a manner to promote quick inflation when deployed asdescribed with respect to the following figures.

In various embodiments, the parachute deployment system has features topromote airflow through a top of the canopy to speed up inflation of theparachute and decrease recoil. Air inflow through the top (canopy) ofthe parachute helps the parachute inflate quickly once the downwardstroke begins, without substantial dropping, by spreading the skirtduring the extension stroke. The manner in which the parachute is packedinto its can affects the speed of inflation. For example, a tightlypacked and rolled parachute inflates slowly and results in more altitudeloss during parachute inflation. The following figures illustrateexamples of how air inflow is promoted by packing the parachute in themanner described.

FIG. 14 is a diagram illustrating an embodiment of a conventionalparachute in a conventional packed state. In this example, the parachuteincludes upper parachute lines 1408, canopy 1410, and lower parachutelines 1412. The cross section at dashed line B is shown as B1. Thecanopy may have vent lines or holes allowing air to pass through andprovide stability while the parachute is in flight. During a packingprocess, the parachute is then compressed and rolled into a cylindricalshape (e.g., where the parachute is rolled up like a sleeping bag orcinnamon bun) as shown in B1 (i.e., so that the hem is no longer loose).Although this form of packing may be appropriate for conventionalparachutes (e.g., without a line constrainer to constrain the upperparachute lines), this type of packing may be less than desirable forparachutes with a line constrainer. The following figure shows a betterpacking shape for such parachutes.

FIG. 15 is a diagram illustrating an embodiment of a parachute in asymmetrically packed state. Packing the parachute symmetrically is goodfor airflow down the center channel, symmetry as the parachute isextracted, and even loading as the parachute reaches full extension.Although not shown herein, in some embodiments the exemplary parachutesystem includes a line restrainer on its upper parachute lines. Thecross section at dashed line B is shown as B2. As shown, there is anopening 1530 that allows air inflow through the canopy. Due to theparachute moving through the air as it is extracted, air is pumpedthrough the parachute through the crown (a center channel of the canopy)to facilitate inflation of the canopy as represented by the airflowarrows.

To help with airflow and more quickly inflate the parachute, theexemplary parachute is packed in an “M” cross-sectional shape designedto inflate quickly. The parachute is packed symmetrically with respectto a longitudinal axis of the parachute. Here, the longitudinal axiscomes out of the page, and parachute material is evenly distributedabout the axis to facilitate even loading upon extraction. By contrast,the packed parachute in FIG. 14 does not have an equal amount ofmaterial distributed around the longitudinal axis. Instead, most of themass is on top of the longitudinal axis, because the location of thecanopy apex is in the bottom layer of the rolled up parachute. Thus,when the parachute in FIG. 14 is extracted, loading is uneven and theparachute needs to unroll before air flows through a center channel ofthe canopy. This tends to make the inflation of the parachute relativelyslow, uneven, and unsteady. To put it another way, instead of rollingthe parachute (as shown in FIG. 14), the parachute is pulled and foldedtogether evenly from all directions toward the longitudinal axis beforebeing compressed in the can. In some embodiments, the hem remains looserather than rolled into the folds of the parachute.

The various embodiments of the disclosed system are capable ofrecovering a payload (e.g., an attached aircraft or person) at lowaltitude and low speed conditions and are also adaptable to high speedor high altitude conditions. The parachute deployment system tolerateshigh loads during initial extraction of the parachute, but actuatesrelease of the rocket with a low load and low recoil. The disclosedsystem may be packed into a small space and is low in mass. In someembodiments, the disclosed parachute deployment system tolerates chaoticextraction and is agnostic to rotation.

Although the foregoing embodiments have been described in some detailfor purposes of clarity of understanding, the invention is not limitedto the details provided. There are many alternative ways of implementingthe invention. The disclosed embodiments are illustrative and notrestrictive.

What is claimed is:
 1. A release assembly for a parachute deployment system, the release assembly comprising: a release back plate configured to couple a rocket tow line to upper parachute lines of a parachute, wherein the release back plate includes a plurality of openings; a first line, wherein the first line passes through a first opening of the release back plate to form a loop holding the rocket tow line in place prior to release; a second line, wherein the second line passes through a second opening of the release back plate to form a loop; and a soft pin coupled to the release back plate and a release line, wherein prior to release, the soft pin is held in place via the loop formed by the second line passing through the release back plate and during release the soft pin is adapted to separate from the release back plate in response to tensioning of the release line causing a parachute to disengage from a rocket.
 2. The release assembly of claim 1, wherein the upper parachute lines are individually looped around the first line, and the first line is looped around the second line.
 3. The release assembly of claim 1, wherein the release assembly is adapted to: attach the parachute to the rocket via the upper parachute lines; and disengage the parachute from the rocket in response to a load shifting from a first load path to a second load path.
 4. The release assembly of claim 1, wherein the release assembly is provided in the parachute deployment system, and the parachute deployment system includes: a parachute coupled to the release assembly via a first load path, wherein the first load path includes the upper parachute lines attached to a canopy of the parachute; the release assembly, wherein the release assembly is adapted to: attach the parachute to the rocket via the upper parachute lines; and disengage the parachute from the rocket in response to a load shifting from the first load path to a second load path; and a line constrainer between the release assembly and the parachute, wherein the upper parachute lines pass through the line constrainer, and the line constrainer is adapted to restrict an extent to which the upper parachute lines are able to extend away from a longitudinal axis of the parachute.
 5. The release assembly of claim 4, wherein the line constrainer includes a flexible piece of material having at least one opening within a threshold distance from a perimeter of the piece of material through which the upper parachute lines pass.
 6. The release assembly of claim 4, wherein the line constrainer includes a cutout permitting airflow through the line constrainer.
 7. The release assembly of claim 4, wherein the line constrainer includes an annular ring having a plurality of openings corresponding to respective ones of the upper parachute lines through which the upper parachute lines extend.
 8. The release assembly of claim 4, wherein the upper parachute lines are connected directly to the release assembly.
 9. The release assembly of claim 4, wherein in response to a malfunction of at least one of the release assembly and the rocket, the upper parachute lines extend without interfering with full inflation of the canopy.
 10. The release assembly of claim 4, wherein the parachute is packed symmetrically with respect to the longitudinal axis such that, on extraction, loading is substantially even and air flows through a center channel of the canopy.
 11. The release assembly of claim 4, wherein the first load path includes at least one lower parachute line, and the second load path extends from the release assembly to a common point with the at least one lower parachute line.
 12. The release assembly of claim 11, wherein the at least one lower parachute line extends from a rim of the parachute to a lower parachute line restrainer.
 13. The release assembly of claim 11, further comprising a lower parachute line restrainer coupled to the parachute via the at least one lower parachute line, wherein, when released, the lower parachute line restrainer permits the at least one lower parachute line to extend in length.
 14. The release assembly of claim 11, further comprising a lower parachute line restrainer coupled to the parachute via the at least one lower parachute line, and adapted to release in response to meeting a threshold force such that the load shifts from the first load path to the second load path.
 15. The release assembly of claim 4, wherein the first load path is configured to be shorter than the second load path before release of a lower parachute line restrainer.
 16. The release assembly of claim 4, wherein the first load path is configured to be longer than the second load path after release of a lower parachute line restrainer.
 17. The release assembly of claim 4, wherein the first load path includes a tow line and the rocket is adapted to tow the parachute via the tow line.
 18. A method of producing a release assembly, the method comprising: providing a release back plate to couple a rocket tow line to upper parachute lines of a parachute, wherein the release back plate includes a plurality of openings; and providing a first line, wherein the first line passes through a first opening of the release back plate to form a loop holding the rocket tow line in place prior to release; providing a second line, wherein the second line passes through a second opening of the release back plate to form a loop; coupling a soft pin to the release back plate and a release line, wherein prior to release, the soft pin is held in place via the loop formed by the second line passing through the release back plate and during release the soft pin is adapted to separate from the release back plate in response to tensioning of the release line causing a parachute to disengage from a rocket.
 19. The method of claim 18, further comprising: individually looping the upper parachute lines around a first line; and looping the first line around a second line.
 20. The method of claim 19, further comprising looping the second line around the soft pin.
 21. The release assembly of claim 1, wherein: the first line passes from a first side of the release back plate to a second side of the release back plate via the first opening of the release back plate; and the second line passes from the first side of the release back plate to the second side of the release back plate via the second opening of the release back plate.
 22. The release assembly of claim 1, further comprising at least one break tie adapted to break and permit the soft pin to separate from the release back plate in response to a threshold release force.
 23. The release assembly of claim 1, further comprising a guide loop adapted to couple the soft pin to the release back plate prior to release, wherein substantially half of the mass of the soft pin is on each side of the guide loop prior to release. 